This background information is provided for the purpose of making known information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information, or the reference in the drawings to “prior art” constitutes prior art against the present invention.
Straddle-type motorized vehicles having an endless track for travelling on snow are well known since at least the 1960's.
Early versions of such motorized tracked vehicles typically incorporated a pair of parallel spaced-apart skis mounted forwardly of the vehicle and connected to a pair of handlebars for steering the vehicle and supporting the front of the vehicle on snow.
Such dual-ski snowmobiles were and remain particularly unsuited for traversing inclined snow-covered slopes. Specifically, due to such dual ski design the vehicle must incline in accordance with the amount of incline of the slope, thereby producing a tendency for the vehicle and operator to roll downhill making such vehicles especially unsafe, as the vehicle may when traversing an inclined slope roll, and more particularly roll over the operator, seriously injuring or killing him/her.
Although some dual-ski snowmobiles, such as that depicted in U.S. Pat. No. 6,923,287, had motor speed reduction gearing mounted in front of the engine rather than beside the engine, and effectively thereby reduced the width of such vehicle, such was more due to limited lateral engine room on a dual ski platform rather than any desire to reduce engine width. Due to the dual ski configuration such models of snow vehicle remained relatively wide and thereby suffered the problems discussed below when traversing inclined slopes.
Single ski motorized tracked vehicles, obviously of lesser width due to the single ski as opposed to the dual ski design, were developed typically from a desire to convert an existing motorcycle to a tracked snow vehicle.
For example, U.S. Pat. No. 8, 910,738 entitled “Snow bike Conversion System”, U.S. Pat. No. 3,822,755 entitled “Kit for Converting Conventional Motorcycle into Snowmobile”, and U.S. Pat. No. 6,431,301 entitled “Snow Vehicle Conversion Kit” together typify prior art kits for converting a motorcycle to a motorized snow vehicle in which the resulting conversion is a snow vehicle having a single ski.
Such kits (and other similar kits) typically provided a single ski which was adapted to be mounted on (or to replace) the front tire of the motorbike, and further provided an endless-track bogey suspension to replace the rear wheel, with motive force to such track and suspension system being supplied by the existing motorcycle motor.
Notably, the resulting snow vehicles arising from such prior art kit conversions were generally extremely unsatisfactory for traversing inclined mountain slopes.
Specifically, motorcycles (and the types mentioned in the aforementioned patents) typically possess kick-activated transmissions mounted to a lateral side of the motor, thus increasing the width of the resulting snow vehicle in the region of the motor, which is typically the region where the operator's legs are positioned when straddling and operating the vehicle. With the added width of the operator's legs, the combined width of the vehicle in the region of the engine causes problems and danger when the operator of the resulting snow vehicle attempts to traverse a steep inclined snow-covered slope. Specifically, when the operator leans such snow vehicle into a steep inclined slope to otherwise prevent sliding down the slope, due to the substantial width the operator's legs will typically contact the up-hill side of the slope resulting in the operator being unable to sufficiently lean the vehicle into the slope of the hill to avoid sliding down the hill. Alternatively, if the operator nevertheless leans into the hill, contact with the operator's uphill leg and the slope causes a buildup of snow on the uphill side of the vehicle preventing further passage of the vehicle along the slope, or alternatively due to forward momentum of the vehicle causes the operator to be brushed off the vehicle by the buildup of snow thereby cause the operator to lose complete control of the vehicle and/or suffer injury.
Various dedicated (i.e non-kit) single-ski snow vehicles have recently been developed and commercially offered for sale.
For example, U.S. Pat. No. 7,475,751 entitled “Snow Vehicle” assigned to Bombardier Recreational Products Inc. teaches such a single-ski non-kit snowmobile, having a forward mounted transverse muffler mounted forward of the engine. Although the possibility of utilizing a continuously variable transmission (CVT) is offered as a possibility (ref. col. 4, lines 9-11), no further details are provided as to how such could be implemented. Moreover, little importance was devoted in such design to reducing the width of the snow vehicle, since such design further provided a fan 69 disposed on the right side of the engine (ref. col. 4, lines 32-33) as shown in FIGS. 2-3 and FIG. 6, as well as a centrifugal clutch 56 likewise mounted on an opposite side of the engine (ref. FIG. 1, 4 & 5). Both of such aforementioned components clearly served to increase the width of the engine, thereby providing relatively large vehicle width when combined with the operator's legs/boots when the operator straddled the vehicle while operating it. Such excess width results in reduced side hill clearance, which in turn limits the amount of incline of a slope that such vehicle would be capable of safely traversing.
Similarly, U.S. Pat. No. 7,789,183 entitled “Personal Snow Vehicle” assigned to Yamaha Motor Corp. likewise teaches a non-kit, single ski motorized snow vehicle. Although such patent extols the advantage (of a single ski) and handle bars as a manner of reduced vehicle width in providing “motorcycle-like” handling (ref. col 8, lines 9-19), such patent nonetheless overlooks engine and powertrain width as a factor in reducing side hill clearance of the vehicle. To the contrary, transmission 44 appears to be mounted on the side of engine 42, and protruding portions 160 on vehicle body frame 20 significantly increase engine width in the region of the operator's legs providing clear evidence that no consideration was given to increasing side hill clearance by eliminating or otherwise repositioning such outwardly extending accoutrements.
Accordingly, a clear need exists for snow vehicle adapted to allow better and more safe traversing of inclined slopes.